Interaction forces between red cells agglutinated by antibody. III. Micromanipulation

Area of Science:

• Biophysics
• Cellular mechanics
• Immunology

Background:

• Previous studies used hydrodynamic forces to measure red blood cell doublet separation.
• The current study utilizes micropipet aspiration for more precise force measurements.
• Human red blood cells cross-linked by anti-B antibody were used.

Purpose of the Study:

• To measure the force of separation of human red blood cell doublets using micropipet aspiration.
• To determine the force required to break a single cross-bridge between red blood cells.
• To investigate the heterogeneity of cell surface adhesion strength.

Main Methods:

• Micropipet aspiration technique was employed to manipulate and separate red blood cell doublets.
• Cells were assembled by aspirating single cells and bringing them into apposition.
• Suction was gradually increased to induce cell separation.

Main Results:

• The mean normal force of separation was 0.45 +/- 0.11 nN at 3.56% antiserum and 0.22 +/- 0.11 nN at 1.22% antiserum.
• These forces were approximately 2.5 times greater than those measured in previous flow studies.
• Data fitted a Poisson distribution, suggesting a force of 0.05 nN to break a single cross-bridge.

Conclusions:

• Micropipet aspiration provides a more sensitive method for measuring cell-cell adhesion forces.
• The force required to break a single cross-bridge is estimated at 0.05 nN.
• Human red blood cell surfaces exhibit nonuniform adhesion strength at both local and population levels.